Point of sale (POS) terminals allow customers to make payments using a variety of payment instruments such as credit cards, debit cards, smart cards, and ATM cards. To ensure that the payment information transmitted from the POS terminals to a payment center is not accessed by unauthorized recipients, this information is typically encrypted and secured (e.g., using digital authentication) during transmission. However, confidential payment information entered by the user into the POS terminal could still be intercepted by tampering with the integrated circuits of the POS terminal. Thieves can use such information to fraudulently receive payment.
POS terminals have a battery backup to maintain storage of confidential information when the power is off. Battery life is an important factor to the life of a POS terminal in the field. To extend battery life, low current consumption from the battery is desirable when the battery powers the POS terminal. Sensors consume current from the battery when sensors are turned on. POS terminals use sensors to detect whether tampering with the POS terminal has taken place. It is desirable to minimize the amount of power consumed by the sensors and systems that control and monitor sensor operations.